/*
 * [New BSD License]
 * Copyright (c) 2011-2012, Brackit Project Team <info@brackit.org>  
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the Brackit Project Team nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.brackit.xquery.module;

import java.util.Collection;
import java.util.Collections;
import java.util.LinkedList;
import java.util.Map;
import java.util.TreeMap;

import org.brackit.xquery.atomic.QNm;
import org.brackit.xquery.compiler.Bits;
import org.brackit.xquery.expr.DeclVariable;
import org.brackit.xquery.expr.DefaultCtxItem;
import org.brackit.xquery.expr.DefaultCtxPos;
import org.brackit.xquery.expr.DefaultCtxSize;
import org.brackit.xquery.expr.Variable;
import org.brackit.xquery.xdm.type.SequenceType;

/**
 * @author Sebastian Baechle
 * 
 */
public class Variables {

	protected final Map<QNm, Variable> vars = new TreeMap<QNm, Variable>();
	protected final DefaultCtxItem dftItem = new DefaultCtxItem();
	protected final DefaultCtxPos dftPos = new DefaultCtxPos(dftItem);
	protected final DefaultCtxSize dftSize = new DefaultCtxSize(dftItem);
	protected LinkedList<Variables> imports = new LinkedList<Variables>();

	public Variables() {
	}

	public boolean isDeclared(QNm name) {
		return vars.containsKey(name);
	}

	public DefaultCtxItem getDftCtxItem() {
		return dftItem;
	}

	public DefaultCtxPos getDftCtxPos() {
		return dftPos;
	}

	public DefaultCtxSize getDftCtxSize() {
		return dftSize;
	}

	public Variable resolve(QNm name) {
		Variable var = vars.get(name);
		if (var != null) {
			return var;
		} else if (name.equals(Bits.FS_DOT)) {
			return dftItem;
		} else if (name.equals(Bits.FS_POSITION)) {
			return dftPos;
		} else if (name.equals(Bits.FS_LAST)) {
			return var;
		}
		for (Variables v : imports) {
			// TODO check only public vars!
			var = v.resolve(name);
			if (v != null) {
				return var;
			}
		}
		return null;
	}

	public void importVariables(Variables variables) {
		imports.add(variables);
	}

	public DeclVariable declare(QNm name, SequenceType type, boolean external) {
		DeclVariable var = new DeclVariable(name, type);
		vars.put(name, var);
		return var;
	}

	public Collection<Variable> getDeclaredVariables() {
		return Collections.unmodifiableCollection(vars.values());
	}
}
